Fin system

ABSTRACT

A fin collar including a body having a proximal region locatable adjacent to an underside of a water craft. The fin collar also including a distal region, the body including a longitudinally extending slot adapted to receive a watercraft fin, the slot extending through the body between the proximal and distal regions. An outer surface of the body includes a fluid flow modification surface which extends around a perimeter of the body.

The present application is a continuation-in-part application filingunder 35 U.S.C. 111(a), which continuation-in-part application claimspriority to International Application No. PCT/AU2010/001500, filed Nov.10, 2010, which claims priority to Australian Patent Application No.2010900949, filed Mar. 8, 2010 and Australian Patent Application No.2009905484, filed Nov. 10, 2009, which applications are incorporatedherein fully by this reference.

FIELD OF THE INVENTION

The present invention relates to a fin system. In particular, thepresent invention relates to a fin system for use on surfboards.However, it will be appreciated by those skilled in the art that the finsystem may be applied to other watercraft such as kite boards,windsurfers and the like.

BACKGROUND OF THE INVENTION

In traditional surfboard design, the fins (or skegs) are permanentlyfixed to the underside of a surfboard. Such fixed fins, or “glassed in”fins utilise a fillet of fibre glass around the perimeter of the finbase which helps to stiffen the connection region between the fins andthe board. The permanent glassed in fins provide minimal waterturbulence, reduced cavitation and laminar flow around the fin andsurfboard interface, which results in increased tail lift during turningand planing, providing greater turning ability, speed and control. Assuch, glassed in fins are often preferred by serious and professionalsurfers.

The fillet connection between the fin and the underside of the surfboardincreases the hydrodynamic properties of the board, as it reduces thewater turbulence and cavitation in the region of the connection.However, such traditional permanent fixation systems do not allow thesurfer to readily change fins for different surf conditions, or removethe fins for transportation. Accordingly, during transportation the finsincrease the overall thickness of the board at the tail end, making itdifficult to transport multiple boards, and increasing the risk ofdamage to the surfboards. In addition, if the surfer intends to haveboards which are set up for various different wave conditions, it isnecessary to carry a selection of different boards.

When surfing, with conventional fixed fins, the surfboard body tends tobe damaged if the fin impacts with an object such as a submerged rock orsand bar, as the fins are often snapped from the board resulting indamage to the adjacent region of the underside.

In contrast to permanent fins, existing removable fins generally providea fin in which the base intersects the underside of the board at anangle which is close to perpendicular. This provides unfavourablehydrodynamic flow properties in the region where the base of the finjoins the underside of the surfboard, which can result in waterturbulence, cavitation and reduced performance characteristics.

OBJECT OF THE INVENTION

It is an object of the present invention to substantially overcome or atleast ameliorate one or more of the above disadvantages, or to provide auseful alternative.

SUMMARY

In a first aspect, the present invention provides a fin collarcomprising: a body having a proximal region locatable adjacent to anunderside of a water craft, and a distal region, the body including alongitudinally extending slot adapted to receive a watercraft fin, theslot extending through the body between the proximal and distal regions,wherein an outer surface of the body includes a fluid flow modificationsurface which extends around a perimeter of the body.

The fluid flow modification surface is preferably a fillet curve, suchthat when the collar is located on a fin, a tangent of the fillet curveat the distal region of the collar adjacent to the slot is substantiallycoincident with an adjacent region of the fin, and a tangent of thefillet curve adjacent to the underside of the water craft issubstantially coincident with the underside of the water craft.

The proximal region is preferably laterally thicker than the distalregion, such that when a fin is located in the slot, and the fin collaris located adjacent to a base of the fin, the fluid flow modificationsurface adjacent to the distal end is substantially coincident with anadjacent surface of the fin.

The body is preferably made from an elastically deformable material.

One or more projections preferably extend away from the proximal region,the projections being engageable with a fin box.

The fin collar preferably includes one or more tabs located at theproximal region, the tabs being adapted to be positioned under a basesurface of the fin such that when the fin is fitted to a watercraft, thetabs inhibit the fin collar from being removed from the fin.

The outer surface of the body at the proximal region preferably includesone or more recesses adapted to provide access to a fastener forsecuring or removing the fin.

A trailing end of the collar is preferably open, such that the slot canbe enlarged to permit a fin to be located within the slot.

The fin collar further preferably comprises a clasp defined by a firstprojection formed on a first side of the body, and a second projectionformed on a second opposing side of the body, wherein when a fin is inengagement with the collar, the first and second projections each extendbeneath a base of the fin and project away from the underside of thewatercraft, to define a pair of fingers, each finger being located on anopposing side of the fin.

The fluid flow modification surface is preferably one of a chamfer,concave, convex, sawtooth, undulating, bulbous and stepping surface orcombination of surfaces.

The collar is preferably manufactured by co-moulding or shrink fitting,and the collar is securable to a groove or channel formed in the fin.

One or more holes are preferably locatable in the fin to assistadhesion.

In a second aspect, the present invention provides a fin systemincluding a fin box adapted to be fitted to a watercraft and a fin,

-   -   the fin including a body with a base portion mountable to an        underside of the watercraft, and a fin tip located at an        opposing end of the fin, the base portion including a mounting        tab and a skirt which extends away from the fin tip generally        around a perimeter of the base;    -   the fin box including a longitudinally extending body having a        receptacle adapted to receive the mounting tab, the body having        an upper surface, a groove being formed in the upper surface,        the groove being adapted to receive the skirt, and the groove        being deeper than the skirt.

The fin preferably includes a fillet curve profile, which defines areduction in thickness of the fin between the base portion and the body.

The fin box preferably includes a lower surface, the lower surface beinggenerally parallel to the upper surface, and extending around theperimeter of the fin box, wherein a step extends between the uppersurface and the lower surface.

The step is preferably chamfered.

One or more breaks are preferably formed in the skirt to provide accessto a fastener receiving hole formed on the upper surface.

A recess is preferably formed in a wall of the receptacle, the recessbeing adapted to receive a projection of a fin collar.

In a third aspect, the present invention provides a fin system includinga fin box adapted to be fitted to a watercraft and a fin,

-   -   the fin box including:        -   a longitudinally extending receptacle having first and            second fin box side walls and an opening, a first plane            extending across the opening of the fin box and being            generally coplanar with the surface of the watercraft in the            vicinity of the fin box;        -   a longitudinally extending first rib located on the first            fin box side wall; and    -   the fin including:        -   a body having a leading edge, a trailing edge, a first side            face and an opposing second side face, the side faces            extending between the leading and trailing edges, a second            plane defined by and including the leading and trailing            edges,        -   a base portion having a first side having a longitudinally            extending first slot and a second side having a shoulder, a            thickness of the base being greater than the thickness of            the body, a fastener receiving hole extending through the            base portion from the first side face to the second side            face;    -   wherein the base portion is insertable into the receptacle in a        first position in which an acute angle is defined between the        first and second planes, and the first rib is located in the        first slot; and    -   further wherein the fin is pivotable to a second position in        which the first and second planes are generally perpendicular,        the first rib remains located in the first slot and the shoulder        is located in the receptacle; and    -   a fastener is insertable into the fastener receiving hole to        engage the shoulder and inhibit removal of the base portion from        the receptacle.

The fastener receiving hole preferably extends diagonally, such that anentry to the hole is closer to a fin tip than an exit to the hole.

In a fourth aspect, the present invention provides a fin systemincluding a fin box adapted to be fitted to a watercraft and a fin,

-   -   the fin box including:        -   a receptacle having a receptacle opening; and        -   the fin including:            -   a fin body having a leading edge, a trailing edge, and                opposing hydrodynamic surfaces extending generally                between the leading and trailing edges, and            -   a mounting tab having a proximal portion adjacent to the                fin body and a distal portion extending away from the                fin body, the mounting tab being insertable within the                receptacle opening and having a first surface and an                opposing second surface, a fastener receiving hole                extending through the mounting tab, the fastener                receiving hole having a first opening located on the                first surface and a second opening located on the second                surface;        -   wherein the fastener receiving hole is diagonally oriented            such that the second opening is closer to the distal end            than the first opening.

A side wall of the receptacle preferably includes a recess adapted toreceive a leading portion of a fastener projecting from said secondopening.

A portion of the fin box adjacent to the receptacle opening preferablyincludes a fastener access channel.

The fastener receiving hole is preferably threaded.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several aspects described belowand together with the description, serve to explain the principles ofthe invention. Like numbers represent the same elements throughout thefigures.

FIG. 1 is a schematic view showing a collar of the present inventionbeing fitted to a fin having a base plate;

FIG. 2 is a schematic view showing a collar of the present inventionbeing fitted to a fin without a base plate;

FIG. 3 is a schematic view showing a collar of the present inventionbeing fitted to a fin from the underside;

FIG. 4 is a partial cross-sectional view showing a collar being securedto a fin with grub screws;

FIG. 5 is a partial cross-sectional view showing a co-moulded collar;

FIG. 6 is a top view depicting a two part collar in an open position;

FIG. 7 is a top view depicting the two part collar of FIG. 6 in a closedposition;

FIG. 8 is a partial cross-sectional view showing an adhesive mounted twopart collar;

FIG. 9 partial cross sectional view depicting a collar fitted to a fin;

FIG. 10 is a top view of a collar according to an alternativeembodiment;

FIG. 11 is a bottom view of the collar of FIG. 10;

FIG. 12 is a bottom view of a set of three collars according to a stillfurther embodiment;

FIG. 13 is a top view of the set of three collars according to FIG. 12;

FIG. 14 is a top view of a collar of an alternative embodiment;

FIG. 15 is a top view of a two part collar of an alternative embodiment;

FIG. 16 is an end view showing a plurality of different collars havingdifferently shaped water contact surfaces;

FIG. 17 depicts a two part collar being fitted to a fin having a baseplate;

FIG. 18 is a partial cross-sectional view of the collar of FIG. 17fitted to a fin;

FIG. 19 is a perspective view of a fin box;

FIG. 20 is a side cross-sectional view of the fin box of FIG. 19;

FIG. 21 is an end cross sectional view of the fin box of FIG. 19;

FIG. 22 is an end view of the fin box of FIG. 19;

FIG. 23 is side view of a collar;

FIG. 24 is a side view of a fin;

FIG. 25 is a perspective underside view of the fin of FIG. 25;

FIG. 26 is a cross sectional view of the fin box of FIG. 19, adapted toreceive a fin mounted on an angle;

FIG. 27 is a rear perspective detail of a fin tab;

FIG. 28 is a front perspective view of the fin tab of FIG. 27;

FIG. 29 is a schematic view showing the fin table of FIG. 27 beingsecured to a fin box with a grub screw;

FIG. 30 is a top view of a fin box of a further embodiment;

FIG. 31 is a partial cross-sectional side view of the fin box of FIG. 30with a fin fitted;

FIG. 32 is a partial cross sectional side view of the fin and collar ofFIG. 12;

FIG. 33 is a partial perspective view showing the collar of FIG. 5mounted to a fin;

FIG. 34 is a collar and fin assembly of a further embodiment;

FIG. 35 is a perspective view of a plug type fin box according to afurther embodiment;

FIG. 36 is a perspective view of a plug type fin box according to afurther embodiment;

FIG. 37 is a perspective view of a fin box according to a furtherembodiment;

FIG. 38 is a perspective view of a fin box according to a furtherembodiment;

FIG. 39 is a schematic cross sectional view of the plug of FIG. 36including a fin;

FIG. 40 is a schematic cross sectional view of the plug of FIG. 35including a fin; and

FIG. 41 is a perspective bottom view of the embodiment of FIG. 37.

DETAILED DISCRIPTION OF THE INVENTION

The following description of the invention is provided as an enablingteaching of the invention in its best, currently known embodiment. Tothis end, those skilled in the relevant art will recognize andappreciate that many changes can be made to the various aspects of theinvention described herein, while still obtaining the beneficial resultsof the present invention. It will also be apparent that some of thedesired benefits of the present invention can be obtained by selectingsome of the features of the present invention without utilizing otherfeatures. Accordingly, those who work in the art will recognize thatmany modifications and adaptations to the present invention are possibleand can even be desirable in certain circumstances and are a part of thepresent invention. Thus, the following description is provided asillustrative of the principles of the present invention and not inlimitation thereof

As used throughout, the singular forms “a,” “an” and “the” includeplural referents unless the context clearly dictates otherwise. Thus,for example, reference to “a fin” can include two or more such finsunless the context indicates otherwise.

As used herein, the terms “optional” or “optionally” mean that thesubsequently described event or circumstance may or may not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

A fin system 20 including a fin box 100 and a fin 40 for use on awatercraft such as a surfboard 60 is described herein.

As depicted in FIG. 1, the fin system 20 includes a collar 70 whichprovides a hydrodynamic adaptor between the underside of the surfboard60, and the fin 40. The collar 70 is shown schematically in FIGS. 1 and2 being fitted over a fin 40. As shown in FIG. 1, the collar 70 isinitially pushed over the tip 42 of the fin 40, and pushed toward theunderside of the surfboard 60 until the collar 70 is located at the base44 of the fin 40, adjacent to the underside of the surfboard 60.

There are several different embodiments of the collar 70 describedherein, which each provide different mounting methods, to suit variousfin boxes. Each embodiment of the collar 70 alters the flow of water inthe interface region between the surfboard and the fin, to providefavourable hydrodynamic performance conditions to the surfer.

In the embodiment of FIGS. 1 and 2, the collar 70 has a body 72 and alongitudinally extending central aperture or slot 74. The slot 74 isdesigned to generally correspond with the size and shape of the fin 40at the base 44 of the fin 40. The collar 70 may be manufactured from anelastically deformable material, such as a rubber compound, oralternatively a more rigid plastic or fibre glass.

In the embodiment shown in FIG. 2, the central aperture 74 defines aflange or lip which is smaller than the fin 40 at the base 44, such thatthe collar 70 is designed to stretch to correspond with the base 44. Thecollar 70 may be fitted over the fin 40 by sliding over the tip, orplacing it under the base prior to installation of the fin 40.

In this embodiment, when the collar 70 is fitted to the fin 40, theassembled fin 40 and collar 70 are then fitted to the surfboard 60. Inthis embodiment, in order to remove the collar 70 from the surfboard 60it is generally necessary to remove the fin 40 from the surfboard 60,and subsequently pull the collar 70 away from the underside of the finbase 44.

The collar 70 body 72 has an outer, perimeter which has a surface 75which provides increased hydrodynamic properties. The surface 75 isgenerally provided having a fillet curved profile. However, othersuitable profiles such as chamfered or angled may be applied to thesurface 75. As shown in FIG. 16, the surface 75 may be a chamfer asshown in example 1, a less curved chamfer as example 2, a straightfillet, with a step as per example 3, a bulbous, convex profile as perexample 4, or various stepping or sawtooth, scalloped or undulatingprofiles as shown in examples 5 to 8.

In the preferred embodiment, the fillet curved surface 75 provides asmooth transition between the underside of the surfboard 60 and the fin40 body. Accordingly, a tangent of the fillet curved surface 75 at anupper portion of the collar 70 adjacent to the slot 74 is substantiallycoincident with an adjacent region of the fin 40. In addition, a tangentof the fillet curved surface 75 adjacent to the underside of thesurfboard 60 may be substantially coincident with the underside of thesurfboard 60.

In some embodiments, the collar 70 includes one or more projections 76.The projections 76 are received by a fin box 100, which is discussed indetail below.

In the embodiment shown in FIGS. 1 and 4, the collar 70 includes one ormore threaded through holes 80. The holes 80 enable fasteners such asgrub screws 82 to be screwed through the holes 80 and driven intoabutment with the side walls of the fin 40, or into the fin box 100. InFIG. 4, the grub screws 82 are depicted being fastened with a hand heldtool, such as a hex key.

In some embodiments such as FIG. 4, a cavity 84 is provided between thecollar 70 and the underside of the surfboard 60. Adjacent to the cavity84 a skirt 86 extends around the perimeter of the collar 70. The skirt86 abuts directly against the underside surface of the surfboard 60, andthe skirt 86 may be flexible or rigid and provides good contact betweenthe surfboard and 60 and collar 70. In an alternative embodimentdepicted in FIG. 26, the base of the skirt 86 is received in a grooveformed in the fin box 100.

It is common for the underside of a surfboard 60 to have a slightlyconvexed contour between the tip and tail of the surfboard 60 in thevicinity of the fins 40. In order to accommodate the convexed contour,the flexible material characteristics of the collar 70 enable theunderside of the collar 70 to adopt a slightly concaved profile toclosely follow the contour surface of the surfboard 60. By having grubscrews 82 at two independent locations along the length of the fin 40between the leading edge and the trailing edge, it is possible to securethe collar 70 in the concaved profile, ensuring good hydrodynamic flowconditions.

Advantageously, the collar 70 does not provide any structural support tothe fin 40. Accordingly, the structural integrity of the fin 40 will notbe affected in the instance that the collar 70 is damaged.

In the embodiment of FIGS. 10 to 15, the collar 70 is designed tocorrespond with the shape of a standard FCS™ style fin system 20. Inthis embodiment, the slot 74 includes enlarged portions 77 which receivethe mounting tabs 46 on base of the FCS™ style fins. In order to securethe collar 70 to the fins 40, the lips 79 sit under the base of the fin40, and the lips 79 are narrower than the width of the fins 40 at thebase. Accordingly, the lips 79 become compressed between the fin box 100and the base of the fins 40, thereby inhibiting removal of the fins 40.In this embodiment, the collar 70 may be either placed over the tip ofthe fin 40 and slid downwardly, or alternatively, the collar 70 may beplaced under the base of the fin 40, prior to securing the fin 40 to thesurfboard 60.

In the embodiment depicted in FIG. 15, the collar 70 is in the form oftwo opposing collar halves 92, 94. Each collar half 92, 94 is placed onan opposing side of the fin 40. The collar halves 92, 94 may be securedto one or both of the underside of the surfboard 60 and the base of thefin 40 with double sided tape, or another suitable adhesive such as hookand loop fasteners or glue.

In the embodiment of FIG. 5, the fin 40 has a notch or channel 98 formedin each of the side walls. The notches 98 extend, between the leadingand trailing ends of the fin 40. In this embodiment, the inner wall ofthe collar 70 is grafted, infused, co-moulded, shrink fitted orotherwise attached to the notch 98. The notch 98 inhibits removal of thecollar 70 from the fin 40. FIG. 34 depicts a similar embodiment, inwhich the two sides of the collar are secured to the fin 40 by way ofthe holes 49 which are formed in the fin. The holes 49 permit adhesiveor a portion of the collar 70 when heated to flow into the holes 49,resulting in higher bond strength.

In one embodiment the collar 70 does not surround the full perimeter ofthe fin 40. In contrast, the collar 70 is located at the leading edge ofthe fin 40 having the most impact on the hydrodynamic properties of thefin 40, and the collar 70 extends along the sides of the fin 40 towardthe trailing end. Accordingly, the collar 70 has a generally U-shapedprofile.

In the embodiment shown in FIGS. 12 to 14, the collar 70 is adapted tobe opened during installation, to facilitate easy securing to thesurfboard 60 and fins 40. In this embodiment, the collar 70 has twosides 200, 202. At the leading edge of the fin 40, the sides 200, 202are connected together with either a clip or a permanent hinge 204. Asshown in the embodiment of FIG. 15, this connector utilises a male hookshaped projection 230 on one of the sides 202 and a corresponding femaleshaped groove 232 on the other side 200. This enables the sides 200, 202to snap together around the fin. In this embodiment, at the trailingend, the sides 200, 202 are secured to the surfboard 60 with grub screwsor another suitable fastener.

In the embodiment of FIGS. 10 to 15, there are flanges or tabs 210 whichare seated beneath the fin 40. The flanges 210 are configured to belocated in between and in front or behind the fin mounting tabs providedwith FCS™ style fins. The tabs 210 prevent the collar from beingunintentionally removed from the surfboard 60. In order to mount thecollar, the sides 200, 202 are closed around the fin 40, about the clipor permanent hinge 204. When the collar 70 is in position, the tabs 210are beneath the base of the fin 40, and the tabs 210 prevent the collar70 from being moved away from the underside of the surfboard 60.

As shown in FIGS. 12 to 14, the two sides of the collar 70 may beintegrally formed such that the collar 70 has a generally “U”-shapedprofile. In this embodiment, the collar material is resilient whichenables the trailing end of the collar 70 to be opened to attach itaround the base of the fin 40. In this embodiment, a fastener such as agrub screw or a pin or a clip 220 is used to connect the two ends of thecollar 70 around the fin.

In the embodiment of FIGS. 12 and 13, at the trailing end of the collar70, there is a clasp in the form of a first projection 232 formed on thefirst side 200, and a second projection 234 formed on the second side202. The projections 232, 234 each extend beneath the base of the fin 40and project away from the underside of the surfboard 60, to define apair of fingers 236, 238. The fingers 236, 238 are shown as a detail inFIG. 32, and they prevent the trailing end of the collar 70 from beingseparated away from the fin, and as such, the fingers 236, 238 lock thecollar 70 in position around the fin 40. Each finger 236, 238 engageswith the opposing side of the fin 40, having the effect of pulling thetwo sides 200, 202 of the collar 70 together. In this embodiment, thecollar 70 may be held in place simply by the fact that it is bounded bythe surf board 60 and the underside and base edges of the fin 40. Assuch, there is no need to use fasteners such as grub screws to hold thecollar 70 in position. As shown in FIG. 13, the collar 70 has holes orapertures 250.

The apertures 250 correspond in placement with the mounting screws whichare used to remove or tighten the fin 40 within the fin box 100.Accordingly, during installation, the collar 70 is initially placedbeneath the base of the fin 40, and the fin 40, with one step 236, 238on either side of the fin 40. The fin 40 is then placed in the fin box.A hex key or other such fastening tool is inserted through the apertures250, and the hex key is used to engage grub screws in the fin box. Theapertures 250 may be elongate to accommodate variations in the placementof the grub screws in the fin box 100.

FIG. 34 discloses an embodiment in which the fin 40 has a base plate 47.The base plate 47 is used to hold and secure the collar 70. The baseplate 47 includes two or more protrusions 300, which fit intocorresponding recesses 302 formed in the underside of the collar 70. Inorder to secure the collar 70, to the base plate 47, a hole 305 isformed in the collar 70, and a fastener such as a grub screw which isinserted into the hole passes through a corresponding hole 307 in theprotrusion 300, and into a downwardly directed second protrusion 310formed on the underside of the collar 70. The base plate 47 may besecured to the fin box 100 with adhesive prior to mounting the collar70.

Advantageously, the steps 236, 238 obviate the need for a grub screw orother such mounting system at the trailing end of the fin 40.

FIGS. 19 to 22 show a fin box 100 for mounting to the underside of asurfboard 60. The fin box 100 includes one or two slots 102. The slots102 receive mounting tabs 46 which extend away from the base of atypical FCS™ style fin. A grub screw receiving hole 104 is formed oneither side of the fin box 100, adjacent to one of the slots 102. On anopposing side of each slot 102 relative to the grub screw receiving hole104 is a recess 106, which is formed in the side wall of the slot 102.The recess 106 is adapted to receive the projection 76 of the collar 70.

Accordingly, when a fin 40 with a collar 70 fitted over the base thereofis fitted to a surfboard 60, the mounting tabs 46 enter into the slots102, and the collar projections 76 enter into the recesses 106. Bytightening the grub screws 82 located in each of the grub screwreceiving holes 104, the grub screws abut against the mounting tabs 46,which in turn compress the projections 76 in the recesses 106. Thisresults in the fin 40 and collar 70 both being secured to the fin box100. During this installation process, the projection 76 is compressed,between the mounting tabs 46 and the walls of the recesses 106.

FIGS. 19 to 22 show that the fin box 100 has a base surface 110, and araised surface 112 raised above the base surface 110. A groove 114 isformed in the raised surface 112, and the groove 114 has a shape whichcorresponds to the outer profile of the base of the fin 40, or collar70.

During manufacture of a surfboard 60, the fin box 100 may be embedded inthe underside of the surfboard 60. Fibre glass and resin is laid overthe base surface 110. Accordingly, surface 110 is subsequently locatedbeneath the outer fibre glass surface of the surfboard 60, and the fibreglass and resin helps to keep the fin box 100 in position. However, theunderside of the surfboard 60 has a slight convex curved formed in itwhich varies slightly in different types of surfboards 60. Accordingly,the raised surface 112 is initially flat, and is sanded to correspondwith the convex contour on the underside of the surfboard 60. Thistypically means that the sanding difference between the highest andlowest points is around 1 mm. The installed fin box 100 is depicted inFIG. 26.

The groove 114 is sufficiently deep that even after the raised surface112 is partially sanded back, (especially in the vicinity of the leadingand trailing ends), there is still a groove 114 extending a majority ofthe way around the perimeter of the fin 40.

As depicted in FIGS. 24 and 25, the fin 40 of this embodiment has anintegrally formed fillet curved base 120, and the underside of the fin40 has a perimeter skirt or flange 122 which has the same general shapeas the groove 114.

Accordingly, after the sanding is completed, the perimeter skirt 122 isinsertable in the groove 114, resulting in a smooth, even transitionbetween the base of the fin 40 and the underside of the surfboard 60.The perimeter skirt 122 may be between 1 and 20 mm deep. In thepreferred embodiment, the perimeter skirt is about 2 mm deep. The groove114 has a depth which is larger than the perimeter skirt 122, typically2-3 mm. Advantageously, this creates a buffer zone for sanding theunderside of the surf board 60. The sander does not need to worry aboutthe exact depth that he sands down to. In addition, the underside of thefin 40 has a concave hollow which helps accommodate any discrepancies inthe levels once the fin box 100 is installed. During installation, thefin box 100 is installed, and covered with tape or a lid. The fin box100 is then set into the board with a laminate resin and fibre glasscloth is applied over the top with a laminate resin.

The perimeter skirt 122 may extend all around the complete perimeter ofthe fin 40. Alternatively, the perimeter wall 122 may have a breakcorresponding to the positions of the grubs screw receiving holes 104.The underside of the fin 40 has a sight concave curve to match theunderside convex curve in the surfboard 60. This typically accounts fora 0.2 to 2 mm difference in height between a leading edge of the fin 40,and a central, underside region of the fin 40.

Advantageously, the fin system of this embodiment enables adjustment ofthe positioning of the fin box 100 by simply sanding away the excessraised surface 112. This reduces the need for accuracy when installingthe fin boxes 100, and hence assists in speeding up the surfboard 60making process.

FIG. 20 represents a partial cross sectional view of the fin box 100. Ascan be seen in that figure, there is an angled chamfer transitionbetween the base surface 110 and the raised surface 112. As shown inFIGS. 19 to 22, the fin box 100 has a generally elliptical outer shape.The mounting tab 46 receiving slots may be in a double formation, formounting typical FCS™ style fins 40. Alternatively, a single channel maybe provided, for standard single tab. Also a single tab may be used formounting FUTURE™ style fins 40. The elliptical profile reduces stresscracking in the adjacent fibre glass of the surf board 100.

As shown in FIG. 25, on the underside of the fin 40, there is a coredout hollow region 124 within the perimeter skirt 122.

FIGS. 29 to 31 show an alternative embodiment of a fin 40. As can beseen from FIG. 24, in this embodiment, the grub screw receiving holes104 are formed in the fin 40, rather than the fin box 100. This isadvantageous because if the threads formed in the grub screw receivingholes 104 are damaged in some way, it is only necessary to replace thefin 40, rather than install a new fin box 100, which is a complicatedprocess, requiring the surfboard 60 to be out of action for aconsiderable period of time.

FIG. 29 is an end sectional view of the fin 40 positioned within acorresponding fin box 100. As can be seen in this figure, the grubscrews 82 pass diagonally downwardly from one side of the fin 40, andemerge on the opposing side of the fin 40 at the base 44.

The mounting tabs 46 of the fin 40 of this embodiment have a first side130 (being the same side as the head of the grub screw 82) and aprojection 133 is formed on the fin box 100, for engaging with a channel135 formed in the base of the fin 40. The opposing second side 132 ofthe mounting tabs 46 do not include projections, but instead, the tipsof the grub screws 82 project away from the mounting tabs 46 and engagewith channels 137 formed on the fin box 100.

In the embodiment shown in FIG. 30, the fin box 100 may be used withproprietary fins 40, as depicted in FIGS. 27, 28. However, the box 100is versatile and may be used with other brand fins 40 such as FCS™ orRAPTOR™. In the instance of FCS™ style fins 40, the mounting tabs 46 arepartially received in the slots 180. In this embodiment, grub screws arereceived in the holes 182. In this embodiment when the box 100 is usedwith FCS™ style fins 40, a plate having a generally elliptical body isplaced over the box 100, and the elliptical body has two generallyrectangular holes for receiving the mounting tans 46 of the fin.

FIG. 30 shows a fin box 100 which is installed in the base of thesurfboard 60 after sanding of the underside of the board 60. In thisembodiment, the base of the fin 40 sits slightly above the perimeter ofthe fin box 100, and a smooth transition is achieved by applying a lightstrip of resin around the edges of the fin box 100. The resin may berounded, concaved or chamfered, or another suitable profile.

As shown in FIG. 12, the existing grub screws which are employed in FCS™and Future™ style fin systems to mount the fins to the board can also bemodified to include a set of smaller grub screws which screw into theheads of the existing grub screws. As such, the smaller grub screws 222are used to mount the collar 70 to the board 60, and this obviates theneed to make any modifications to the structure of the board 60 or finbox 100.

FIG. 35 discloses a generally circular fin box 400. Similar to theembodiment of FIGS. 29 to 31, in this embodiment, threaded holes 104 areformed in the mounting tabs 46 of the fin 40, rather than the fin box400, for receiving grub screws or other suitable fasteners. This isadvantageous because if the threads formed in the grub screw receivingholes 104 are damaged in some way, it is only necessary to replace thefin 40, rather than install a new fin box 400, which is a complicatedprocess, requiring the surfboard 60 to be out of action for aconsiderable period of time.

A vertical wall 401 of the fin box 400 includes a recess 402 which thehead of the grub screw abuts against. This applies a force against thefin box 400, and the retention shoulder 404 inhibits the mounting tabs46 of the fin 40 from being pulled out of the box 400. In the embodimentof FIG. 35 the fin box 400 includes an angled grub screw receivingchannel 406, which provides a clearance for the grub screw and grubscrew tool or key.

In the embodiment of FIG. 36 the fin box 440 is similar to theembodiment of FIG. 35. However, there is no grub screw receiving channel406 in this embodiment. In contrast, the angle of the grub screw passesthrough the mounting tabs 46 of the fin 40 at a more acute angle. Thisis depicted schematically in FIG. 39. In contrast, FIG. 40 depicts theembodiment of FIG. 35 as a side cross sectional view, showing the angleof the grub screw receiving hole passing through the mounting tabs 46 ofthe fin 40 at a less acute angle.

FIG. 37 depicts a fin box 460 which is adapted to receive both mountingtabs 46 of a single fin 40. The installation and removal of a fin 40into the fin box 460 is similar to the embodiment shown in FIG. 36, asthe grub screws are inserted through the mounting tabs 46. A perimeterportion of the of the box 460 includes a plurality of notches or grooves462 which assist with bonding to fibreglass resin during manufacture ofthe surfboard.

FIG. 38 depicts a fin box 480 of a further embodiment. In thisembodiment the fin box 480 is similar to the embodiment of FIG. 37,however the fin box 480 of FIG. 38 further includes an angled grub screwreceiving channel 482, which provides a clearance for the grub screw andgrub screw tool or key.

The fin boxes 460, 480 of FIGS. 37 and 38 are typically intended to beinstalled pre-fibreglass installation during the surf board duringmanufacture. In contrast, the plug style fin boxes of FIGS. 35 and 36are intended to be installed post fibreglass installation.

As shown in FIG. 41, the fin boxes 460, 480 may include additionalnotches or grooves 464 on the underside or base of the fin box 460, 480.

Although several embodiments of the invention have been disclosed in theforegoing specification, it is understood by those skilled in the artthat many modifications and other embodiments of the invention will cometo mind to which the invention pertains, having the benefit of theteaching presented in the foregoing description and associated drawings.It is therefore understood that the invention is not limited to thespecific embodiments disclosed herein, and that many modifications andother embodiments of the invention are intended to be included withinthe scope of the invention. Moreover, although specific terms areemployed herein, they are used only in a generic and descriptive sense,and not for the purposes of limiting the described invention.

1. A fin collar comprising: a body having a proximal region locatableadjacent to an underside of a water craft, and a distal region, the bodyincluding a longitudinally extending slot adapted to receive awatercraft fin, the slot extending through the body between the proximaland distal regions, wherein an outer surface of the body includes afluid flow modification surface which extends around a perimeter of thebody.
 2. The fin collar of claim 1, wherein the fluid flow modificationsurface is a fillet curve, such that when the collar is located on afin, a tangent of the fillet curve at the distal region of the collaradjacent to the slot is substantially coincident with an adjacent regionof the fin, and a tangent of the fillet curve adjacent to the undersideof the water craft is substantially coincident with the underside of thewater craft.
 3. The fin collar of claim 1, wherein the proximal regionis laterally thicker than the distal region, such that when a fin islocated in the slot, and the fin collar is located adjacent to a base ofthe fin, the fluid flow modification surface adjacent to the distal endis substantially coincident with an adjacent surface of the fin.
 4. Thefin collar of any one of the preceding claims, wherein the body is madefrom an elastically deformable material.
 5. The fin collar of any one ofthe preceding claims, wherein one or more projections extend away fromthe proximal region, the projections being engageable with a fin box. 6.The fin collar of any one of the preceding claims, including one or moretabs located at the proximal region, the tabs being adapted to bepositioned under a base surface of the fin such that when the fin isfitted to a watercraft, the tabs inhibit the fin collar from beingremoved from the fin.
 7. The fin collar of any one of the precedingclaims, wherein the outer surface of the body at the proximal regionincludes one or more recesses adapted to provide access to a fastenerfor securing or removing the fin.
 8. The fin collar of any one of thepreceding claims, wherein a trailing end of the collar is open, suchthat the slot can be enlarged to permit a fin to be located within theslot.
 9. The fin collar of claim 8, further comprising a clasp definedby a first projection formed on a first side of the body, and a secondprojection formed on a second opposing side of the body, wherein when afin is in engagement with the collar, the first and second projectionseach extend beneath a base of the fin and project away from theunderside of the watercraft, to define a pair of fingers, each fingerbeing located on an opposing side of the fin.
 10. The collar of any oneof the preceding claims, wherein the fluid flow modification surface isone of a chamfer, concave, convex, sawtooth, undulating, bulbous andstepping surface or combination of surfaces.
 11. The collar of any oneof claims 1 to 4, wherein the collar is manufactured by co-moulding orshrink fitting, and the collar is securable to a groove or channelformed in the fin.
 12. The collar of claim 11, wherein one or more holesare locatable in the fin to assist adhesion.
 13. A fin system includinga fin box adapted to be fitted to a watercraft and a fin, the finincluding a body with a base portion mountable to an underside of thewatercraft, and a fin tip located at an opposing end of the fin, thebase portion including a mounting tab and a skirt which extends awayfrom the fin tip generally around a perimeter of the base; the fin boxincluding a longitudinally extending body having a receptacle adapted toreceive the mounting tab, the body having an upper surface, a groovebeing formed in the upper surface, the groove being adapted to receivethe skirt, and the groove being deeper than the skirt.
 14. The finsystem of claim 13, wherein the fin includes a fillet curve profile,which defines a reduction in thickness of the fin between the baseportion and the body.
 15. The fin system of claim 13 or 14, wherein thefin box includes a lower surface, the lower surface being generallyparallel to the upper surface, and extending around the perimeter of thefin box, wherein a step extends between the upper surface and the lowersurface.
 16. The fin system of claim 15, wherein the step is chamfered.17. The fin system of claim 13, wherein one or more breaks are formed inthe skirt to provide access to a fastener receiving hole formed on theupper surface.
 18. The fin system of any one of claims 13 to 17, whereina recess is formed in a wall of the receptacle, the recess being adaptedto receive a projection of a fin collar.
 19. A fin system including afin box adapted to be fitted to a watercraft and a fin, the fin boxincluding: a longitudinally extending receptacle having first and secondfin box side walls and an opening, a first plane extending across theopening of the fin box and being generally coplanar with the surface ofthe watercraft in the vicinity of the fin box; a longitudinallyextending first rib located on the first fin box side wall; and the finincluding: a body having a leading edge, a trailing edge, a first sideface and an opposing second side face, the side faces extending betweenthe leading and trailing edges, a second plane defined by and includingthe leading and trailing edges, a base portion having a first sidehaving a longitudinally extending first slot and a second side having ashoulder, a thickness of the base being greater than the thickness ofthe body, a fastener receiving hole extending through the base portionfrom the first side face to the second side face; wherein the baseportion is insertable into the receptacle in a first position in whichan acute angle is defined between the first and second planes, and thefirst rib is located in the first slot; and further wherein the fin ispivotable to a second position in which the first and second planes aregenerally perpendicular, the first rib remains located in the first slotand the shoulder is located in the receptacle; and a fastener isinsertable into the fastener receiving hole to engage the shoulder andinhibit removal of the base portion from the receptacle.
 20. The finsystem of claim 19, wherein the fastener receiving hole extendsdiagonally, such that an entry to the hole is closer to a fin tip thanan exit to the hole.
 21. A fin system including a fin box adapted to befitted to a watercraft and a fin, the fin box including: a receptaclehaving a receptacle opening; and the fin including: a fin body having aleading edge, a trailing edge, and opposing hydrodynamic surfacesextending generally between the leading and trailing edges, and amounting tab having a proximal portion adjacent to the fin body and adistal portion extending away from the fin body, the mounting tab beinginsertable within the receptacle opening and having a first surface andan opposing second surface, a fastener receiving hole extending throughthe mounting tab, the fastener receiving hole having a first openinglocated on the first surface and a second opening located on the secondsurface; wherein the fastener receiving hole is diagonally oriented suchthat the second opening is closer to the distal end than the firstopening.
 22. The fin system of claim 21, wherein a side wall of thereceptacle includes a recess adapted to receive a leading portion of afastener projecting from said second opening.
 23. The fin system ofclaim 21 or 22 wherein a portion of the fin box adjacent to thereceptacle opening includes a fastener access channel.
 24. The finsystem of any one of claims 21 to 23 wherein the fastener receiving holeis threaded.